Structural unit for a gas exchange valve train of an internal combustion engine

ABSTRACT

A structural unit for a gas exchange valve train of an internal combustion engine is provided. The structural unit includes a support element ( 8 ) having a joint head ( 7 ) and a valve lever ( 1 ) having a joint socket ( 6 ) which, together with the joint head, forms a joint for a pivotal mounting of the valve lever on the support element. The structural unit further includes an anti-loss device arranged on the joint, with the anti-loss device having one or more projections ( 11 ) extending from the opening of the joint socket while being directed toward the center of the joint socket, which projections retain the valve lever secure against loss on the support element through a positive-engagement behind a recess situated axially adjacent to the joint head. The invention further provides that the projections are configured in one piece with the joint socket.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/324,431, filed Apr. 15, 2010, which is incorporated herein by reference as if fully set forth.

BACKGROUND

The invention concerns a structural unit for a gas exchange valve train of an internal combustion engine. The structural unit comprises a support element comprising a joint head and a valve lever comprising a joint socket which, together with the joint head, forms a joint for a pivotal mounting of the valve lever on the support element, said structural unit further comprising an anti-loss device arranged on the joint, said anti-loss device comprising one or more projections extending on the opening of the joint socket while being directed toward the center of the joint socket, which projections retain the valve lever secure against loss on the support element through a positive-engagement behind a recess situated axially adjacent to the joint head.

Structural assemblies of the pre-cited type made up of a valve lever and a support element serve to minimize the risk of a possible mounting error of the valve lever in the internal combustion engine. The mounting error could particularly consist in that the valve lever is mounted twisted through 180° in the gas exchange valve train. In the case of a valve lever with an end-side mounting, the contact partners, joint head of the support element and joint socket of the valve lever, could switch positions with the associated contact surface on the valve lever. This would lead at least to a malfunctioning of the valve train, and in the worst case, to serious damage to the engine. The anti-loss device thus has the function of reliably excluding a falling-apart of the structural unit due to transportation movements before it is mounted in the internal combustion engine.

The anti-loss device is usually a retention clip made as a separate part and mounted on the valve lever. Prior art retention clips are made of flat or round stock as disclosed, for instance in DE 196 17 523 A1. The positive-engagement connection between the valve lever and the support element is realized by the fact that during insertion of the joint head into the joint socket, the projections of the retention clip are elastically spread away from the center of the joint socket to subsequently snap into the recess under the joint head.

In contrast to anti-loss devices acting through friction-locking, as known from U.S. Pat. No. 6,047,675 to be made out of wire material or out of sheet metal from DE 10 2005 036 918 A1, positive-engagement anti-loss devices provide an unobstructed pivotal moving ability of the valve lever on the support element.

SUMMARY

The object of the present invention is to provide a structural unit of the aforesaid type with less complexity and/or lower manufacturing costs.

This object is achieved through the features of the invention, while advantageous developments and embodiments of the invention are described below and in the claims. According to the invention, the projections are configured in one piece with the joint socket. In other words, the invention omits the hitherto used retention clip which is made as a separate component from the valve lever and the support element and has to be mounted in a separate assembly step and replaces its function through the projection or projections integrated in the valve lever.

Advantageously, the valve lever comprises a lever body that is shaped out of sheet metal and is therefore less expensive, each of the projections being integrally formed on the lever body by an embossing or a stamping of the material delimiting the joint socket and said projections being directed toward the opening of the joint socket. The valve lever can be a finger lever which is centrally loaded through the lift of a cam, one end section of the lever body being mounted on the support element and the other end section of the lever body serving to actuate the gas exchange valve. It is further also possible to use a rocker arm centrally mounted on the support element, wherein the one end section of the lever body is loaded by the lift of a cam and the other end of the lever body serves to actuate the gas exchange valve. Alternatively to the lever body shaped out of sheet metal, it may be required in specific fields of use to provide a lever body shaped by forming by casting, forging or sintering, in which case the projections are integrally formed by a corresponding shaping of the creative forming tool.

Preferably, two projections offset from each other by 180° are provided. According to a further proposition of the invention, these projections are oriented relative to the joint socket such that, a connecting line of the projections extends at right angles to the plane of pivoting of the valve lever. In this arrangement, the projections extend in the relatively weakly loaded region of the joint socket, so that the size of the highly loaded contact surfaces of the joint socket extending in the plane of pivoting remains unprejudiced as compared to prior art anti-loss devices using retention clips.

Different to the above proposition, it is also conceivable to use any number, shape and position of the projections. Thus, even a single, preferably circumferentially extending projection or at least three projections may be provided which, in addition, may have identical or different shapes and/or may be arranged equally or unequally spaced on the circumference.

According to a further development of the invention, at the transition to the recess configured as a circumferential undercut, the joint head is completely circular in shape. The inner spacing of the projections is smaller than the largest diameter of the joint head and is dimensioned such that the projections are elastically resilient relative to the joint head at the largest diameter of the joint head. In other words, with the exception of a possibly provided flattened region on its joint socket-side pole, the joint head is completely spherical and an adjoining annular groove is provided under the joint head as is the case in prior art support elements. The otherwise usual retention clip is replaced by the fact that, during the assembly of the structural unit, the projections deflect elastically relative to the joint head when this is pressed into the joint socket during assembly and then snap into the annular groove thus forming a positive-engagement anti-loss device.

In an alternative embodiment, at the transition to the recess, the joint head is circular in shape and comprises flattened regions complementary in shape to the projections. The inner spacing of the projections is smaller than the largest diameter of the joint head and substantially equal to or larger than the outer spacing of the flattened regions. In contrast to the aforesaid completely spherical joint head, the assembly of this structural unit is performed in that the projections and the flattened regions are oriented radially aligned to each other during the then low-force insertion of the joint head into the joint socket to be twisted subsequently relative to each other to form the positive-engagement anti-loss device. In the case of two identically shaped, opposing projections and flattened regions arranged at 180° from each other, a twisting angle of 90° is appropriate. To preclude the improbable case that, during transportation of the structural unit, the joint head gets turned back into the assembly position and the anti-loss device thus becomes ineffective, it is possible to provide a comparatively low-strength elastic snap connection of the projections behind the flattened regions.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention will become apparent from the following description and from the appended drawings in which examples of embodiment of the invention are illustrated. If not otherwise stated, identical or functionally identical components or features are identified by the same reference numerals. The figures show:

FIG. 1, a valve lever according to the invention in a perspective underside view of the joint socket;

FIG. 2, a support element according to the invention in a perspective side view of the joint head;

FIG. 3, a structural unit made up of the valve lever of FIG. 1 and the support element of FIG. 2;

FIG. 4, a prior art support element in a perspective side view for forming a structural unit according to the invention comprising the valve lever of FIG. 1;

FIG. 5, the valve lever of FIG. 1 in a perspective top view of the joint socket;

FIG. 6, the structural unit of FIG. 3 in a cross-sectional view; and

FIG. 7, a partial view of a prior art gas exchange valve train.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be explained with reference to FIG. 7 in which a part of a prior art gas exchange valve train of an internal combustion engine is illustrated. A valve lever configured as a finger lever 1 comprises a lever body 2 which is made by cold shaping out of a sheet metal and possesses on a first end section a contact surface for actuating the gas exchange valve 3 and carries in its center section a rolling bearing-mounted roller 4 which serves as a low-friction contact surface for the cam 5 of a camshaft. On the second end section of the lever body 2 is formed a cup-shaped joint socket 6′ which forms a joint with a spherical joint head 7′ of a, in the present case, hydraulic valve lash adjusting support element 8 mounted statically in the internal combustion engine. Through the thus formed joint, the finger lever 1 is mounted for pivoting on the support element 8. By a retention clip 9 arranged on the joint, the finger lever 1 and the support element 8 are assembled together into a structural unit secured against loss by the fact that the retention clip 9 engages into a recess in the form of an annular groove 10 extending under the joint head 7′ and axially adjoining the joint head 7′, and that the retention clip 9 engages positively behind the joint head 7′.

A finger lever 1 according to the invention for forming a structural unit secured against loss in which a separate component as an anti-loss device is neither necessary nor provided, is disclosed in FIG. 1. The anti-loss feature is created through projections 11 which are formed integrally with the joint socket 6 and extend on the opening of the joint socket 6 while being directed toward the center of the joint socket 6. The two identically configured projections 11 are arranged offset at 180° from each other and oriented such that a connecting line of the projections 11 extends at right angles to the plane of pivoting of the finger lever 1.

The structural unit illustrated in FIG. 3 can be formed out of the finger lever 1 of FIG. 1 and the support element 8 of FIG. 2. At the transition to the axially adjoining annular groove 10, the joint head 7 of the support element 8 is circular in shape and comprises two flattened regions 12, only one being visible in the figure, and have a shape complementary to that of the projections 11. The inner spacing of the projections 11 identified at S1 and the outer spacing of the flattened regions 12 identified at S3 are substantially equal in size, while the inner spacing S1 of the projections 11 is clearly smaller than the largest diameter S2 of the joint head 7 at the transition to the annular groove 10 and—for the purpose of an unobstructed pivoting ability of the finger lever 1—obviously, somewhat larger than the diameter of the annular groove 10. The assembly of the structural unit is performed in that the projections 11 and the flattened regions 12 are oriented radially aligned to one another to enable a low-force insertion of the joint head 7 into the joint socket 6. For forming the positive-engagement anti-loss device, the projections 11 and the flattened regions 12 are then twisted through about 90° relative to each other, as illustrated in FIG. 3.

A structural unit (not illustrated) according to the invention can also be formed by the finger lever 1 of FIG. 1 and a prior art support element 8 of FIG. 4 whose joint head 7 likewise has a spherical shape but is completely circular in shape at the transition to the adjoining annular groove 10. In this case, the projections 11 are configured to be elastically yielding relative to the joint head 7 at the largest diameter S2 of the joint head 7 at the transition to the annular groove 10. Thus, when the joint head 7 is pressed into the joint socket 6, the projections 11 can deflect in radial direction and form the positive-engagement anti-loss device behind the joint head 7 by snapping into the annular groove 10. The elastic yielding character of the projections 11 is achieved through their appropriate shaping and dimensioning, the inner spacing S1 of the projections 11 being somewhat smaller than the largest diameter S2 of the joint head 7.

The projections 11 are created by a cold shaping step of the lever body 2 made of sheet metal, and FIGS. 5 and 6 show the result of this shaping step. FIG. 5 shows a view of the closed side of the joint socket 6 with two stampings 13 directed toward the opening of the joint socket 6 and made in the material delimiting the joint socket 6. FIG. 6 shows in a cross-sectional view through the joint socket 6, the projections 11 generated on the joint socket 6 through the stampings 13.

LIST OF REFERENCE NUMERALS

-   -   1 Valve lever/finger lever     -   2 Lever body     -   3 Gas exchange valve     -   4 Roller     -   5 Cam     -   6 Joint socket     -   7 Joint head     -   8 Support element     -   9 Retention clip     -   10 Annular groove/recess     -   11 Projection     -   12 Flattened region     -   13 Stamping     -   S1 Inner spacing of the projections     -   S2 Largest diameter of the joint head     -   S3 Outer spacing of the flattened regions 

1. A structural unit for a gas exchange valve train of an internal combustion engine, said structural unit comprising a support element comprising a joint head and a valve lever comprising a joint socket which, together with the joint head, forms a joint for a pivotal mounting of the valve lever on the support element, said structural unit further comprising an anti-loss device arranged on the joint, said anti-loss device comprising one or more projections extending from an opening of the joint socket while being directed toward a center of the joint socket, which projections retain the valve lever secure against loss on the support element through a positive-engagement behind a recess situated axially adjacent to the joint head, wherein the projections are configured in one piece with the joint socket.
 2. A structural unit according to claim 1, wherein the valve lever comprises a lever body shaped out of sheet metal, each of the projections being integrally formed on the lever body by an embossing or a stamping of material delimiting the joint socket and said projections being directed toward the opening of the joint socket.
 3. A structural unit according to claim 1, wherein the two projections are offset at 180° from each other.
 4. A structural unit according to claim 3, wherein a connecting line of the projections extends at right angles to a plane of pivoting of the valve lever.
 5. A structural unit according to claim 1, wherein, at a transition to the recess configured as a circumferential undercut, the joint head is completely circular in shape, an inner spacing (S1) of the projections being smaller than a largest diameter (S2) of the joint head while being dimensioned such that the projections are elastically resilient relative to the joint head at the largest diameter (S2) of the joint head.
 6. A structural unit according to claim 1, wherein, at a transition to the recess, the joint head is circular in shape and comprises flattened regions complementary in shape to the projections, an inner spacing (S1) of the projections being smaller than a largest diameter (S2) of the joint head and substantially equal to or larger than an outer spacing (S3) of the flattened regions. 